The present invention relates generally to electrical communications systems and, more particularly, to such systems with particular safety functions.
As society has moved into the 21st Century, some of its disaffected members have resorted to acts of extreme violence and terror as a way of being heard. Some of these acts have taken the lives of thousands of people and have injured thousands more. Unfortunately, no one foresees an end to such acts. It is, of course, desirable to warn targeted groups well in advance of such a terrorist act so that precautions can be taken to avoid or minimize the expected harm.
To a certain extent, mass mediaxe2x80x94radio and television in particularxe2x80x94is effective in rapidly alerting the public of impending, ongoing and completed acts of terrorism. One drawback of relying solely upon radio and television to provide alerts of terrorist activities is that detailed instructions from governmental leaders cannot be provided to those directly involved in providing for the health, safety and welfare of a group of people such as doctors, firemen, and police. The problem of communicating is compounded by our system of government where federal, state and local responsibilities overlap. Thus, it can be difficult to provide a coordinated response to a terrorist threat, natural disaster or similar event.
In light of the drawbacks associated with using broadcast media to rapidly and accurately disseminate information important to public health, safety and welfare, it is a principal object of the invention to provide an emergency warning network that could be used only by authorized personnel to notify specified people of impending dangers. These dangers might include: terrorist alerts and advisories, fires, explosions, chemical spills, hostage takings, radiation leaks, and the spread of biological agents or gasses to name a few. Apart from news regarding dangers, real time-critical information related to weather and earth movements can be delivered to interested parties by the network.
It is a further object of the invention to provide an emergency warning network of the type described that can be employed to provide time-critical information to users associated with federal, state and local governmental entities in a manner that permits an orderly chain of command to be maintained at all times. Users positioned xe2x80x9con the groundxe2x80x9d are able to obtain the information wherever they may be located: at home, in the field, in a vehicle, etc.
It is another object of the invention to provide an emergency warning network of the type described that alerts users of its activation with an audible and visual alarm. Once the alarm has sounded, detailed information may be obtained audibly or visually.
It is an object of the invention to provide improved elements and arrangements thereof in an emergency warning network for the purposes described that is rugged in construction, inexpensive to manufacture, easy to use, and dependable in operation.
Briefly, the emergency warning network in accordance with this invention achieves the intended objects by featuring a base station for broadcasting a warning signal via a first, earth-orbiting satellite to a pair of substations. After receiving warning signal, one substation broadcasts a forwarding signal carrying the message from the base station, perhaps in a modified form, to at least one portable receiver. The other substation broadcasts a similar signal via a second, earth-orbiting satellite to a pair of branch stations. In turn, the branch stations broadcast forwarding signals to one or more portable receivers.
The foregoing and other objects, features and advantages of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawing.